Robert Arthur Wiles, 26, was last seen April 1 at National Flight Services, his family's business, where he worked as a business development manager. The business is located at Lakeland Linder Regional Airport.

FBI officials investigating the disappearance have classified it as a kidnapping.

FBI spokesman Dave Couvertier said Wiles' family discovered a ransom note April 3 and "aggressively responded," complying with its instructions and demands. They haven't heard anything since from the person who left the note, Couvertier said.

"We are worried about Robert. We love Robert, and we are seriously worried about his safety," said his mother, Pamela Wiles. "We will do anything we can to bring our son back and get him home safely."

Robert Wiles' parents, Thomas and Pamela, made their plea from the FBI's Tampa field office, as law enforcement officials made their first public statements about the kidnapping. The FBI is involved in the case because of the ransom note.

Couvertier released no information about the note's contents or how the Wiles have so far complied. He cited the ongoing investigation as the reason.

Investigators have this message to the person or persons who sent the ransom note: The Wileses have no way of knowing if you received their response to the demands. Contact them using the same name used in the note.

Couvertier said investigators have developed "individuals of interest" in the case. Leads from associates of Wiles have led investigators to Tampa, Lakeland, Orlando, Brevard, Sarasota, Fort Myers, Miami, Key West, Melbourne, Kentucky, Ohio, Tennessee and Thailand.

Robert Wiles' parents say he is a licensed pilot, a diver, an athlete and a journeyman fisherman. He is described as 5-feet-9, 165 pounds with hazel eyes and brown hair. He was last seen around 6:30 p.m. April 1.

Anyone with information about Wiles was asked to contact the FBI toll-free at 1 (866) 838-1153 or call the local police.

Times researcher John Martin contributed to this story. Kevin Graham can be reached at kgraham@sptimes.com or (813) 226-3433.